No city council or village board of trustees shall cause to be assessed for any of the improvements authorized pursuant to section 17-913, property by law not assessable, or property not included within the district defined in the preliminary resolution, and shall not assess property not benefited. The cost of sewers at the intersection of streets and alleys and opposite property belonging to the United States Government, or other property not assessable, may be included with the cost of the rest of the work and may be assessed on the property within the district, if benefited by the improvement to such extent, or may be paid from unappropriated money in the general fund. The cost of the improvements shall draw interest from the date of acceptance thereof by the city council or village board of trustees.